(a) The only purpose for adopting the Texas Coordinate System of 1927 and the Texas Coordinate System of 1983 is to recognize a system for use in the State of Texas to definitely ascertain positions on the surface of the earth.
(b) Except as provided in Section 21.041 of this code, the use of a system is not required, and the provisions of this subchapter shall not be construed to set aside or disturb any corner or survey already established.

(c) The use of the term “Texas Coordinate System” on a map, report, survey, or other document is limited to coordinates based on a Texas Coordinate System as defined in this subchapter.